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Subject[PATCH v3] serial: pch_uart: potential dereference of null pointer
Date
The return value of dma_alloc_coherent() needs to be checked.
To avoid dereference of null pointer in case of the failure of alloc.
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
Changelog:

v2 -> v3

*Change 1. Remove dev_err.
*Change 2. Change the return type of pch_request_dma to int.
*Change 3. Return -ENOMEM when dma_alloc_coherent() failed and 0 the
others.
*Change 4. Check return value of dma_alloc_coherent().
---
drivers/tty/serial/pch_uart.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index f0351e6f0ef6..cfad5592010c 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -698,7 +698,7 @@ static bool filter(struct dma_chan *chan, void *slave)
}
}

-static void pch_request_dma(struct uart_port *port)
+static int pch_request_dma(struct uart_port *port)
{
dma_cap_mask_t mask;
struct dma_chan *chan;
@@ -723,7 +723,7 @@ static void pch_request_dma(struct uart_port *port)
if (!chan) {
dev_err(priv->port.dev, "%s:dma_request_channel FAILS(Tx)\n",
__func__);
- return;
+ return 0;
}
priv->chan_tx = chan;

@@ -739,13 +739,20 @@ static void pch_request_dma(struct uart_port *port)
__func__);
dma_release_channel(priv->chan_tx);
priv->chan_tx = NULL;
- return;
+ return 0;
}

/* Get Consistent memory for DMA */
priv->rx_buf_virt = dma_alloc_coherent(port->dev, port->fifosize,
&priv->rx_buf_dma, GFP_KERNEL);
+ if (!priv->rx_buf_virt) {
+ dma_release_channel(priv->chan_tx);
+ priv->chan_tx = NULL;
+ return -ENOMEM;
+ }
+
priv->chan_rx = chan;
+ return 0;
}

static void pch_dma_rx_complete(void *arg)
@@ -1321,8 +1328,11 @@ static int pch_uart_startup(struct uart_port *port)
if (ret < 0)
return ret;

- if (priv->use_dma)
- pch_request_dma(port);
+ if (priv->use_dma) {
+ ret = pch_request_dma(port);
+ if (ret)
+ return ret;
+ }

priv->start_rx = 1;
pch_uart_hal_enable_interrupt(priv, PCH_UART_HAL_RX_INT |
@@ -1469,6 +1479,7 @@ static int pch_uart_verify_port(struct uart_port *port,
struct serial_struct *serinfo)
{
struct eg20t_port *priv;
+ int ret;

priv = container_of(port, struct eg20t_port, port);
if (serinfo->flags & UPF_LOW_LATENCY) {
@@ -1483,7 +1494,9 @@ static int pch_uart_verify_port(struct uart_port *port,
return -EOPNOTSUPP;
#endif
if (!priv->use_dma) {
- pch_request_dma(port);
+ ret = pch_request_dma(port);
+ if (ret)
+ return ret;
if (priv->chan_rx)
priv->use_dma = 1;
}
--
2.25.1
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